Fiat 500 ATF drain plug within a drain plug

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7,365
Location
Suburban Washington DC
Did a drain and refill on 2012. First time I've seen a set up like this. There is a small drain plug, removed with a T40, that on most cars covers an opening used to adjust the fluid level at a certain temperature by allowing AFT to overflow a tube in the pan if the fluid level is too high. With the Fiat the level is checked with a dipstick through the top fill hole. The dipstick doesn't come with the car but is a tool you can buy.

Anyway, that small drain plug is screwed into a large drain plug. With the small one out, you can use a 17mm hex, either a bit or key, to remove the big one which drains the majority of the fluid. This is an Aisin Warner unit. Do any of their other transmissions have a setup like this dual drain plug? I like that you can actually check the level from the top, and can thus, theoretically do frequent refills with an extractor. Will do a second refill today trying my extractor to see how much fluid it can remove from the top.
 
Messages
1,336
Location
Ontario, Canada
Did a drain and refill on 2012. First time I've seen a set up like this. There is a small drain plug, removed with a T40, that on most cars covers an opening used to adjust the fluid level at a certain temperature by allowing AFT to overflow a tube in the pan if the fluid level is too high. With the Fiat the level is checked with a dipstick through the top fill hole. The dipstick doesn't come with the car but is a tool you can buy.

Anyway, that small drain plug is screwed into a large drain plug. With the small one out, you can use a 17mm hex, either a bit or key, to remove the big one which drains the majority of the fluid. This is an Aisin Warner unit. Do any of their other transmissions have a setup like this dual drain plug? I like that you can actually check the level from the top, and can thus, theoretically do frequent refills with an extractor. Will do a second refill today trying my extractor to see how much fluid it can remove from the top.
Same system in Toyota/Lexus trannies made by Aisin.
 
Messages
7,456
Location
Los Gatos, CA
I quite like them. Drain the fluid, measure the fluid drained and refil adding an extra 100ml or so. Get it upto temp, remove the smaller screw and it will drain down to the right level.
That's what I do. But given that the top of the fluid is the top of the fluid, a dipstick does the same thing.
 
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